I have an R donor bike (with the more rounded profiled headlight shell vs the slightly squarer-edged one on the V model), and the glass on my V bike has got a huge crack in it (a gritter lorry I suspect – one came past me in the other direction the other day when I was doing about 70 and it HURT. I'd like to be able to just swap the whole headlight shell. I'm supposed to be biking down to London and back on Sunday (400 miles total) so need to change it tomorrow. On Valentine's day – my girlfriend will be THRILLED.

You're in luck. They're completely interchangeable. My bike, a '96 T, is wearing a '99 X lens and rim mated to the original '96 bowl. In fact, I preferred the look of the earlier bowl.

You're good to go! Also, you will find that the wiring harness is a bastard to get back in. Top tip, don't plug in any block connectors until you've got the main harness into the cable guides. It DOES all go back in!

I agree, I prefer the earlier one too! More old-school somehow. This is great news, thanks for the reply. So could I actually change just the rim without even changing the bowl? Although in a way I'd like to change the whole thing...

Oh yes, the older bowl has captive nuts. Mine was definitely a direct swap though.... I also had an improved spread of light - because my original reflector had gone all milky; the silvery bit is quite delicate.

And by the way...I only found that out after I'd taken the bowl off and put the R model one on. What an idiot! I even knew the bolts were different but didn't check the size of the holes in the bracket. Oh well, at least I've now had practice getting the wiring in and out. I actually managed it without unplugging any of the connectors. I had to keep patient though otherwise I'd have definitely damaged something.

So I'm good to go for my 400-mile round trip tomorrow, more or less. Annoyingly I noticed one of my mirrors is broken around the ball joint because of rust – have attempted an epoxy and gaffa tape repair and new mirrors on order.

Also my front brake is binding slightly because the slider pin on the bracket is horribly corroded (oddly the one on the caliper is pristine). I took it off today and cleaned the slider pin and re-greased it, but it's still binding a bit. I have a new bracket with a nice shiny pin on order from ebay, but I'm guessing that it's alright to do a long journey with it binding as it's only mild? Other than fuel economy and slight glazing of the pads (I scuffed them earlier with emery cloth and they're much sharper) is this a stupid idea?

I had this last week. I cured it by: removing the pad retaining pin, pads, then caliper while still connected to the brake hose. I pumped the pistons out A LITTLE WAY, so there's about 3mm twixt line of filth and bottom of piston. Got an old toothbrush and brake cleaner, scrub, scrub, scrub away. If you have a pair, some piston pliers so's you can turn the pistons and clean all round. A smear of red rubber grease round the sides of the pistons, push 'em back in, refit, torque up and pump lever.

Yeah, I did do that as well but I was in a slight hurry (never a good idea) and didn't clean the pistons as thoroughly as I'd have liked. Plus my can of brake cleaner was running out by then! So that's probably not helping, but seriously, you should see the carrier's slider pin. The surface looks like some kind of brown pumice stone! It's odd actually, my rear caliper has exactly the same thing – slider pin on the caliper is fine but on the carrier it's horrendous. Maybe to do with how much spray they get whilst riding in the wet or something – I can't see why they'd be made of different materials. I somehow doubt it's because both calipers have been replaced but not the carriers. Anyway...I have a new carrier waiting to put on the back, and one for the front on its way as I said.

I must get some piston pliers as it always really frustrates me whenever I change my pads not being able to clean the pistons 100%.

Where do you get red rubber grease? I'm currently using silicone grease from Maplin – only place I could find such stuff (£4.99 for a 50g tube : / ).

You can get red rubber grease from your local auto factor. They'll normally sell it in very small quantities because a big tub would be a lifetime supply and it gets contaminated fairly quickly. It's actually vegetable-based which is why it's completely innocuous on your brake parts and won't contaminate your fluid.

I buy brake cleaner by the 5 litre container as it's much cheaper. You will also need a spray bottle and this one, which I have seems to be the industry standard.